1. Field of Invention
The present invention relates to the recombination of soil (i.e. secondary bonding as defined in the field of colloid chemistry) to promote recombination through various substitution processes utilizing specific solutes and the unique properties of soil particles themselves such, as bonding power and rock-forming power.
2. Description of the Prior Art
Many types of soil have a high water content including sludge-like soil existing in the river-bed or at the river-mouth, sand and mud found in water hazards polluted soil from factories, humin rich-soil found at roadside, in slanted ground, or at road construction sites, mountain soil having a low humin content, soil in the area of deforestation (rich in silica content), etc.
According to conventional technologies, solidifying soil is done by using zeolite, bentonite, Portland cement, citric acid, and is a temporary solidification.
The conventional method of solidification is to improve (or modify) soil quality by using zeolite (bentonite) as usual and to solidify (or cluster) soil by utilizing its adsorptive and catalytic actions. In addition, a method for temporary solidification mixes alkaline soil with chlorides of inorganic ions (or metal ions). The soil cement construction method is used for modifying the quality of underground and ground soil and uses specific metal ions by forming coordination compounds (i.e. complex) with citric acid. Another method for a long-term stable solidification of soil is to decompose humin contained in soil. However, techniques are currently not available for sufficient decomposition of the humin component.
The conventional methods of solidification mentioned above only provide temporary solidification. Even the solidification method by mixing soil with cement may not result in sufficient solidification of hazardous substances contained in soil. For instance, the solidification with organic chelating agents (e.g. citric acid) may cause secondary environmental pollution resulting from the elution of heavy metal ions and substances due to the destruction of crystals by the irradiation of UV ray and visible light.
In addition, sulfur compounds exhausted from smokestacks and in exhaust gas will combine with atmospheric moisture to form acid rain which causes the destruction of molecular structure within cement. Namely, cement becomes one of the causes of secondary environmental pollution, despite the fact that cement was originally used as a solidifying agent.
If there is humin component contained in soil, regardless if it is polluted soil or general soil, it will not be solidified (because it contains sugar component) even though cement or bentonite is used as a solidifying agent.
U.S. Pat. No. 5,295,761 describes a method for remediating soils contaminated with hydrocarbons. The method includes the steps of: collecting the contaminated soil; reducing the collected soil to finely-divided particles; applying a controlled amount of consisting essentially of an aqueous solution of sodium silicate, ethylene glycol and sodium methyl silanolate as a spray onto the contaminated soil particles; and aerating the soil particles as the additive is being applied. As will become evident from studying the description in this specification, the process of U.S. Pat. No. 5,295,761 is completely different from the process of this invention. First the process of U.S. Pat. No. 5,295,761 is only intended to remediate soil contaminated with hydrocarbons. It does not treat metallic contamination.
Further, the process of U.S. Pat. No. 5,295,761 involves spraying while the instant invention involves mixing of aqueous solutions. Finally, the process of U.S. Pat. No. 5,295,761 utilizes entirely different chemicals.
Development of a method for permanently solidifying soil including detoxification, stabilization and recombination satisfies a long felt need in the field of soil remediation.
The present invention relates to the recombination of soil (or secondary bonding) based on the theory of substitution of metal complex as focused on various types of substitution in solvation shell.
When considering recombination (secondary bonding or rock forming) of soil in the present invention, the bonding function of various metal oxides (MO, SiO2, Al2O3 where M is metal) is utilized in soil having a diameter less then 2 xcexcm for recombination and rock formation through substitution in a solvent solution at room temperature.
Conversely, if fine particles of various metal oxides having a bonding function can be recombined in a solvent solution, it is possible to form rocks from soil once conditions and environment for recombination are arranged. One of the major inhibitory factors that block recombination is humin (protein, carbohydrate), fatty acids (including glycerin), and organic phosphate that are contained in soil.
The present invention enables the inhibitory factor (or the decomposition of humin) to be eliminated and at the same time to solidify hazardous semi-metal and heavy metal compounds as well as halogenated compounds in a stable state, resulting in making these compounds incorporated into soil. In other words, recombination is made possible by incorporating hazardous organic metals as a component of the soil.
The recombination is a consequence of a series of actual processes including detoxifying and solidifying hazardous semi-metal and heavy-metal compounds in a stable state and incorporating them as the components of soil above. However, it is necessary to separate the procedure into two steps, the preliminary treatment and the technical treatment at the stage of recombination. Therefore, when recombining soil particles the whole process is completed in two separate steps; the removal of the inhibitory factor (e.g. humin) and the detoxification, stabilization, and solidification of hazardous semi-metal and heavy metal compounds and halogenated compounds.
At the second step of the recombination, the hazardous semi-metal and heavy metal compounds and halogenated compounds that underwent detoxification, stabilization and solidification, are in the recombination process when incorporated into the whole as a component of recombination by substituting ligands.
Properties such as non-permeability, permeability, strength tolerance, heat resistance, resilience, saltwater resistance, acid resistance and alkali resistance that are required for actual field soil are the criteria when modifying soil quality according to invention.
The present invention provides the initial treatment in order to prepare the conditions for recombining various components of soil (including a variety of heavy metal compounds, semi-metal compounds, halogenated compounds and other substances), and to isolate and decompose the molecules of humin component (protein, carbohydrate) and fatty acids (including long-chain glycerin) as well as the detoxification and stabilization of hazardous metals in the solvation shell with specified solutes. Through the hydration and solvation effects of such solutes, the humin component of soil as an inhibitory factor against the bonding of soil particles is isolated and decomposed, and at a microscopic level various components of soil particles form metal coordination compounds (or metal complex). The present invention relates to the solute effect and coordination theory, in other words, chemical and physical recombination (or secondary bonding) of soil by providing conditions for establishing electron transfer (outer and inner-sphere mechanisms) of metal coordination compounds.
The present invention also provides a method for manufacturing soil having new properties by modifying soil quality by adding specified additives to the pre-treated soil.
This invention is a further development of the inventors"" prior invention which is disclosed in U.S. Pat. No. 5,986,161. U.S. Pat. No. 5,986,161 discloses a method for neutralizing/detoxifying and stably fixing/solidifying combinations of hazardous compounds. The method comprises the following steps:
adding sodium nitrite and sodium 1-naphthylamine-4-sulfonate to the combinations;
stirring the resultant mixture for about 5 minutes;
allowing the mixture to set for about 10 minutes;
adding either 2-naphthol-4-sulfonic acid or 2-naphthol-7 sulfonic acid, and calcium oxide to the mixture;
stirring the mixture;
allowing the mixture to set for about one hour;
adding graphite;
stirring for about one hour; and
allowing the mixture to set for about one hour.
It will be seen from the description below that the process described in this specification is completely different from the invention described in U.S. Pat. No. 5,986,161. U.S. Pat. No. 5,989,161 does not teach removing inhibitors and specifically does not mention removing humin. Further U.S. Pat. No. 5,989,161 utilizes substantially different chemicals for its process.
An appreciation of the other aims and objectives of the present invention and an understanding of it may be achieved by referring to the following description of a preferred embodiment.